1. Field of the Invention
The present invention relates to an earphone comprising a case that houses an electroacoustic transducer, the case being adapted to be put in the hollow or concha of the flap of an ear known as an auricle.
2. Description of the Prior Art
One earlier earphone has a sound outlet to be inserted into the external auditory meatus of an ear in use. Modern earphones have a case housing an electrostatic transducer, the case being shaped so that it is simply put in the concha of an ear flap or auricle. The case is not inserted into the external auditory meatus of an ear, and hence does not make the user feel uncomfortable. Furthermore, the electroacoustic transducer housed in the case may be of a large size for improved sound quality particularly in a low frequency range. For these reasons, the modern earphone design has gained almost exclusive popularity among earphone users.
One recent earphone disclosed in Japanese Patent Publication No. 64-4398 comprises a housing having an external ear engaging region on the outer periphery of a front portion of the housing, the external ear engaging region being of a circular shape whose diameter is larger than the remainder of the housing. In use, the external ear engaging region is placed in the cavity or hollow of an external ear of the user.
However, if the housing were increased in size to accommodate an electroacoustic transducer of larger size for improved acoustic characteristics, then when the earphone is placed in the cavity of the external ear, it would impose pressure on a dimensionally small ear region between the tragus and an upper portion of the inlet of the external auditory meatus which is contiguous to the antitragus. Therefore, the size of the housing and hence the earphone itself is governed by the dimension between the tragus and the upper portion of the inlet of the external auditory meatus which is contiguous to the antitragus.